The present invention relates to prewinding tools for installing helical coil inserts into tapped holes, and more particularly to a prewinding apparatus selectively attachable to an installation tool.
Helical coil inserts are commonly installed into tapped holes of a work piece so that threaded fasteners, such as screws, can be held more securely. These inserts provide a female thread of a harder material than the material of the original threaded hole, into which they are installed. In other words, the inserts improve the gripping of threaded fasteners made of relatively hard materials, such as various steel alloys, when installed in relatively soft parent materials, such as aluminum. Helical coil inserts typically include a tang used as a grip by a mandrel of the installation tool for screwing the helical coil insert into the tapped hole.
Helical coil inserts of this kind are usually installed by pre-winding then to reduce their diameter, and then rotatably threading them into a tapped hole. Once installed, the inserts expand from their contracted diameters and press radially outward against the walls defining the tapped holes, whereby the insert is securely held in place. Various tool are provided for performing this function, however, these typically are limited to larger single-function tools such as those driven by an air or electric motor. Such tools further include a tubular body having a threaded bore extending along its axis and an opening at one end of the body for placing the insert in the bore. A mandrel is rotated by the motor within the threaded bore and into engagement with the insert. Advancement of the mandrel forces the insert through a prewinder, which contracts the insert prior to advancement into a tapped hole in an adjacent work piece. Once the insert is installed at the correct depth in the bore of the work piece, the mandrel is reversed until it is removed from the insert. Upon removal of the mandrel, the insert expands radially to engage the wall of the tapped hole.
As mentioned above, such installation tools are generally dedicated tools performing the functions of prewinding and installing inserts. In order to perform these functions a special prewinder tool must be purchased. In all manufacturing environments, there is a continuous drive to reduce costs. Having to purchase special tools to perform specific functions significantly increases costs. Therefore, it is desirable in the industry to provide a prewinder apparatus that is adaptable for operation with an existing tool. In this manner, the number of tools may be reduced and ease of use may be improved, thereby significantly reducing overall costs.
Accordingly, the present invention provides a prewinder apparatus selectively attachable to a drive tool for prewinding a helical coil insert. The prewinder apparatus includes a support structure selectively attachable to the drive tool and a prewinder attached to an end of the support structure. The prewinder includes first and second threaded apertures and a mandrel preferably having a threaded end and a coupling end. The threaded end engages the first threaded aperture and selectively engages the second threaded aperture. The coupling end is in selective operable engagement with the drive tool, whereby the drive tool rotatably drives the mandrel relative to the prewinder. Specifically, the mandrel rotatably drives the helical coil insert through the second threaded aperture to prewind the helical coil insert.
In a first preferred embodiment, the prewinder apparatus is a reciprocating mandrel prewinder apparatus. This reciprocating-mandrel prewinder apparatus includes a drive sleeve having a main body with a coupling stem in selective engagement with the drive tool and a cavity for slidably receiving the coupling end of the mandrel therein. The coupling end includes a radially extending pin slidably disposed within a slot running along a length of the drive sleeve. The drive sleeve is rotatably driven by the drive tool for reciprocally driving the mandrel within the prewinder apparatus. The reciprocating mandrel prewinder apparatus preferably includes a pair of adjustable stops operably engageable with the drive sleeve to define a range of sliding motion of the mandrel relative thereto.
In a second preferred embodiment, the prewinder apparatus is a stationary mandrel prewinder apparatus. The mandrel of the stationary-mandrel prewinder apparatus is rotatably driven by the drive tool, thereby reciprocally driving the support structure of the stationary-mandrel prewinder apparatus relative to the drive tool. For facilitating movement of the support structure, the support structure includes a slot for slidably engaging the drive tool. The stationary-mandrel prewinder apparatus preferably includes an adjustable stop, which is adjustable along a length of the mandrel to define a range of sliding motion of the support structure relative to the drive tool.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.